Light-emitting diode (LED) light sources are commonly and widely used for direct-lit backlight illumination. Computers, personal digital assistants (PDAs), mobile phones, and thin liquid crystal display (LCD) televisions (TVs) are a few examples of backlight screen devices that use direct-lit LED backlights. However, the light intensity distribution range of LEDs is narrow, so a lens may be used on an LED to help distribute the light.
In direct-lit backlight, an array of lenses is placed in front of the light sources to provide a more uniform light output on the surface of the backlight device. A large number of LEDs may be needed depending on the size of the light spot right above the lens, thus increasing the cost. The number of LEDs needed for a backlight can be decreased by increasing the spot size of each individual LED device.